According to one aspect of the present invention, a radar system is provided which accurately measures the surface profile in a wide sector beneath and forward of a helicopter, to aid low level transit and landing in poor visibility. This uses an electronic beam synthesis technique to form multiple beams directed at the area of interest, each measuring the distance to the first reflected signal received by each beam. These distances represent the profile of the ground and any objects on the ground. A processor then compares the measured profile with the ideal ground profile for safe landing. If the deviations from straight and level exceed the specified requirement for safe landing, or if sufficient rotor clearance is not detected, then a warning is given to the operator. A display will show the measured ground profile highlighting the unsafe regions, allowing the operator to seek a safe region to land. The novelty lies in the way the beams are formed to measure and display the ground profile and provide a warning system. This beam-forming technique is simpler and more cost effective than with a conventional phased array radar.
Legal claims defining the scope of protection, as filed with the USPTO.
1. A radar ranging system for imaging the topography of an area of interest, said system comprising: at least one linear array of transmitter elements that transmit transmitter beams comprising a sequence of ranging signals phased to form a beam pattern covering part of the area of interest, the sequence phased to scan the beam pattern over an entire area of interest; at least one linear array of receiver elements arranged orthogonally to the transmitter linear arrays wherein each receiver element receives a time sequence of the ranging signals reflected from variations on the ground as illuminated by the sequence of the ranging signals, the receiver elements each producing a receiver signal; and at least one processor adapted to process each receiver signal, wherein the at least one processor forms a multiplicity of receiver beams complementary to the transmitter beams such that the combination of the transmitter beams and the receiver beams form pencil beams which cover the entire area of interest in time sequence, wherein the at least one processor measures a time delay of a first reflection received in each of the formed pencil beams and converts the time delay into a range measure at each beam angle to form a topographic profile of the area of interest in range and beam angle coordinates.
2. The radar ranging system of claim 1 , wherein the at least one processor is configured to process the topographic profile to display an image of the terrain topography in the area of interest.
3. The radar ranging system of claim 1 , wherein the at least one processor is configured to process the topographic profile in the area of interest to determine if the area of interest is safe for landing an aircraft.
4. The radar ranging system of claim 3 , wherein the at least one processor is configured to provide a warning signal if a hazard is present and configured to show one of: a hazard and a safe area on a display.
5. The radar ranging system of claim 1 , wherein the at least one processor is configured to output a display of the topographic profile as one of: a color display, a contour display, or mesh plot display.
6. The radar ranging system of claim 5 where the display is referenced to a vertical coordinate system.
7. The radar ranging system of claim 5 where the display is referenced to a coordinate system of a platform employing the imaging system.
8. The radar ranging system of claim 5 , wherein the display is presented as an artificial perspective of the ground as viewed from an aircraft platform.
9. The radar ranging system of claim 1 , wherein the topographic profile is further processed to determine a substantially level area within the area of interest.
10. The radar ranging system of claim 9 , wherein the substantially level area is identified on a display of the image of the terrain topography.
11. The radar ranging system of claim 9 , wherein the at least one processor is configured to provide a warning if no substantially level area can be identified.
12. The radar ranging system of claim 11 , wherein the warning comprises an audible warning.
13. The radar ranging system of claim 1 , wherein the transmitter elements and receiver elements comprise transmitter and receiver sub-arrays, respectively.
14. The radar ranging system of claim 1 , wherein a time delay on a first return in each beam is captured and scaled to a range measurement.
15. The radar ranging system of claim 14 , wherein the shortest range measured by all the beams is displayed numerically as radar altitude.
16. The radar ranging system of claim 1 , wherein the at least one processor is further adapted to compare the topographic profile with a threshold value denoting the slope, a level clearance, and a flatness according to pre-specified data to safely land an airborne vehicle within the area of interest and display suitable and unsuitable areas to an operator of the airborne vehicle.
17. The radar ranging system of claim 1 , wherein the at least one processor is adapted to compare the topographic profile with pre-specified profiles needed for safe rotor and tail rotor clearance on approach to the area of interest and display suitable and unsuitable areas for landing.
18. The radar ranging system of claim 1 , wherein the at least one linear array of transmitter arrays comprises two transmitter arrays of 16 elements each operating at about 35 GHz and the at least one linear array of receiver elements comprises two receiver arrays of 16 elements each forming 1024 pencil beams.
19. The radar ranging system of claim 1 , wherein the at least one processor forms a guard channel to mitigate the effect of sidelobe leakage.
20. The radar ranging system of claim 1 , wherein the at least one processor performs a Clean Algorithm on the data streams from all the beams to mitigate any effects caused by sidelobe leakage.
21. The radar ranging system of claim 1 , wherein the radar ranging system is mounted to look down, to assist operators make a vertical landing.
22. The radar ranging system of claim 1 , wherein the radar ranging system is mounted to include a suitable forward look in the area of interest, to assist operators making a forward approach to the landing zone.
Cooperative Patent Classification codes for this invention. Click any code to explore related patents in that topic.
March 19, 2013
May 26, 2015
Browse 5M+ US patents with plain-English claim translations and AI-generated analysis.